As electronics speed moves into the multi-gigahertz regime, component dimensions are shrinking commeasurably. This causes devices to be more sensitive to electrical over-stresses via accidental exposure to unintended voltages. When test and measurement instruments are of low bandwidth such as those state-of-the-art oscilloscopes from a few years ago, many ultra fast single incidence high voltage spikes are essentially undetectable and overlooked. Their presence however, may have caused mysterious unexplained device failures. As oscilloscope bandwidth continued to increase, those ultra fast single-incidence events can now be captured with relative ease. This has led to the discovery of many unexpected voltage spikes generated by some seemingly-harmless structures.
One such anomaly is an unexpected voltage-spiking problem common in 26 GHz mechanical relays. High bandwidth instruments often require signal routing with minimum distortion and insertion loss through different paths for various purposes such as, changing attenuation, filtering, gain controlling, time delaying, phase referencing, etc. Although solid-state switching devices have gained ground in signal switching applications, mechanical relays are still preferred for switching broadband microwave signals where minimum signal distortion, low on-state insertion loss, low off-state signal feed-through, and smooth impedance transitions throughout the signal rerouting are required. Such mechanical relays typically use a studded center (output) connector with as many moveable satellite strip lines as that relay's number of throws. Each of the satellite movable strip lines starts at its corresponding individual connector and ends at the center common connector, and is controlled by a push rod mechanism to place that strip line section, one-at-a-time, to complete the signal path between the center connector and the corresponding satellite connector. The entire strip line structure is completely contained in a fully enclosed Faraday cage.
An exemplary RF relay structure in the 26 GHz bandwidth range is represented by the DB Products (Carson, Calif.) model 2SE1T11JA relay. This relay has been found to produce up to ˜20V peak 200 ps negative pulses each time the relay toggles. This spike voltage does not change polarity as one switches the relay back and forth.